After merge with Plugin branch.

1 files changed, 287 insertions, 0 deletions

diff --git a/lib/coderay/helpers/plugin.rb b/lib/coderay/helpers/plugin.rb
new file mode 100644
index 0000000..b0bb49e
--- /dev/null
+++ b/lib/coderay/helpers/plugin.rb
@@ -0,0 +1,287 @@
+

+# = PluginHost

+#

+# $Id$

+#

+# A simple subclass plugin system.

+# 

+#	Example:		

+#		class Generators < PluginHost

+#			plugin_path 'app/generators'

+#		end

+#		

+#	  class Generator

+#	  	extend Plugin

+#	  	PLUGIN_HOST = Generators

+#	  end

+#   

+#	  class FancyGenerator < Generator

+#	  	register_for :fancy

+#	  end

+#

+#	  Generators[:fancy]  #-> FancyGenerator

+#	  # or

+#	  require_plugin 'Generators/fancy'

+module PluginHost

+

+	# Raised if Encoders::[] fails because:

+	# * a file could not be found

+	# * the requested Encoder is not registered

+	PluginNotFound = Class.new Exception

+

+	PLUGIN_HOSTS = []

+	PLUGIN_HOSTS_BY_ID = {}  # dummy hash

+

+	class << self

+

+		def extended mod

+			PLUGIN_HOSTS << mod

+		end

+

+		def included mod

+			warn "#{name} should not be included. Use extend."

+		end

+

+		# Find the PluginHost for host_id.

+		def host_by_id host_id

+			unless PLUGIN_HOSTS_BY_ID.default_proc

+				ph = Hash.new do |h, _host_id|

+					for host in PLUGIN_HOSTS

+						h[host.host_id] = host

+					end

+					h.fetch _host_id, nil

+				end				

+				PLUGIN_HOSTS_BY_ID.replace ph

+			end

+			PLUGIN_HOSTS_BY_ID[host_id]

+		end

+

+	end

+	

+		def plugin_host_id host_id

+			if host_id.is_a? String

+				raise ArgumentError,

+					"String or Symbol expected, but #{lang.class} given."

+			end

+			

+		end

+

+		# The path where the plugins can be found.

+		def plugin_path *args

+			unless args.empty?

+				@plugin_path = File.join(*args)

+			end

+			@plugin_path

+		end

+

+		# The host's ID.

+		#

+		# If PLUGIN_HOST_ID is not set, it is simply the class name.

+		def host_id

+			if self.const_defined? :PLUGIN_HOST_ID

+				self::PLUGIN_HOST_ID

+			else

+				name

+			end

+		end

+

+		def create_plugin_hash

+			@plugin_hash =

+				Hash.new do |h, plugin_id|

+					id = validate_id(plugin_id)

+					path = path_to id

+					begin

+						puts 'Loading plugin: ' + path if $DEBUG

+						require path

+					rescue LoadError

+						raise PluginNotFound, "#{path} not found."

+					else

+						# Plugin should have registered by now

+						unless h.has_key? id

+							raise PluginNotFound,

+								"No #{self.name} plugin for #{id} found in #{path}."

+						end

+					end

+					h[id]

+				end

+		end

+

+		def plugin_hash

+			@plugin_hash ||= create_plugin_hash

+		end

+

+

+		# Every plugin must register itself for one or more

+		# +ids+ by calling register_for, which calls this method.

+		#

+		# See Plugin#register_for.

+		def register plugin, *ids

+			for id in ids

+				unless id.is_a? Symbol

+					raise ArgumentError,

+						"id must be a Symbol, but it was a #{id.class}" 

+				end

+				plugin_hash[validate_id(id)] = plugin

+			end

+		end

+

+

+		# Returns an array of all .rb files in the plugin path.

+		# 

+		# The extension .rb is not included.

+		def all_plugin_names

+			Dir[path_to('*')].map do |file|

+				File.basename file, '.rb'

+			end

+		end

+

+		# Loads all plugins using all_plugin_names and load.

+		def load_all

+			for plugin in all_plugin_names

+				load_plugin plugin

+			end

+		end

+

+

+		# Returns the Plugin for +id+.

+		# 

+		# Example:

+		#  yaml_plugin = MyPluginHost[:yaml]

+		def [] id, *args, &blk

+			plugin_hash.[] validate_id(id), *args, &blk

+		end

+

+		# Alias for +[]+.

+		alias load_plugin []

+

+		# Returns the Plugin for +id+.

+		# Use it like Hash#fetch.

+		# 

+		# Example:

+		#  yaml_plugin = MyPluginHost[:yaml, :default]

+		def fetch id, *args, &blk

+			plugin_hash.fetch validate_id(id), *args, &blk

+		end

+

+		# Returns the path to the encoder for format.

+		def path_to plugin_id

+			File.join plugin_path, "#{plugin_id}.rb"

+		end

+

+		# Converts +id+ to a downcase Symbol if it is a String,

+		# or returns +id+ if it already is a Symbol.

+		#

+		# Raises +ArgumentError+ for all other objects, or if the

+		# given String includes non-alphanumeric characters (\W).

+		def validate_id id

+			if id.is_a? Symbol

+				id

+			elsif id.is_a? String

+				if id[/\w+/] == id

+					id.downcase.to_sym

+				else

+					raise ArgumentError, "Invalid id: '#{id}' given."

+				end

+			else

+				raise ArgumentError,

+					"String or Symbol expected, but #{id.class} given."

+			end

+		end

+

+	#end

+

+

+end

+

+

+# = Plugin

+# 

+#	Plugins have to include this module.

+#

+#	IMPORTANT: use extend for this module.

+#

+#	Example: see PluginHost.

+module Plugin

+

+	def included mod

+		warn "#{name} should not be included. Use extend."

+	end

+

+	# Register this class for the given langs.

+	# Example:

+	#   class MyPlugin < PluginHost::BaseClass

+	#     register_for :my_id

+	#     ...

+	#   end

+	#

+	# See PluginHost.register.

+	def register_for *ids

+		plugin_host.register self, *ids

+	end

+

+	# The host for this Plugin class.

+	def plugin_host host = nil

+		if host and not host.is_a? PluginHost

+			raise ArgumentError,

+				"PluginHost expected, but #{host.class} given."

+		end

+		self.const_set :PLUGIN_HOST, host if host

+		self::PLUGIN_HOST

+	end

+

+end

+

+

+# Convenience method for plugin loading.

+# The syntax used is:

+#

+#  require_plugin '<Host ID>/<Plugin ID>'

+# 

+# Returns the loaded plugin.

+def require_plugin path

+	host, plugin_id = path.split '/', 2

+	PluginHost.host_by_id(host).load_plugin plugin_id

+end

+

+

+if $0 == __FILE__

+	$VERBOSE = $DEBUG = true

+	eval DATA.read, nil, $0, __LINE__+4

+end

+

+__END__

+

+require 'test/unit'

+

+class TC_PLUGINS < Test::Unit::TestCase

+

+	class Generators

+		extend PluginHost

+		plugin_path '.'

+	end

+

+	class Generator

+		extend Plugin

+		plugin_host Generators

+	end

+

+	class FancyGenerator < Generator

+		register_for :plugin_host

+	end

+

+	def test_plugin

+		assert_nothing_raised do

+			Generators[:plugin_host]

+		end	

+		assert_equal FancyGenerator, Generators[:plugin_host]

+	end

+	

+	def test_require

+		assert_nothing_raised do

+			require_plugin('TC_PLUGINS::Generators/plugin_host')

+		end

+		assert_equal FancyGenerator,

+			require_plugin('TC_PLUGINS::Generators/plugin_host')

+	end

+

+end